Originally Posted by
budawpi
In my experience without boosting either army:
GIBARCH: Better for farming gold & elixir in Gold & Crystal leagues. Heroes help a lot. DE farming is decent in C3 or lower as well. No spells required, though Heal helps when you are getting to the core of a good base. You can BARCH collector raids without needing to use giants too. Better resources per hour. Faster training time.
LOONION: Better for "lazy farming," when you only want to attack once per 45-60 minutes or less. Heroes not necessarily needed. Rage spells almost always required for harder bases, thus more training time and elixir cost. Unable to hit many collector raids without burning a more time-costly chunk of your army (less ideal than the "barch" part of GIBARCH). Stronger for getting DE in high Crystal or Masters leagues, but much less lucrative for elixir. Less resources per hour.
Edit: to answer your first question, I would vote archers then giants.